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Mr. Tom Schreiner, Division of Minerals and Geology March 23, 2005 Page 10 ~~ CIVIL RES'~URCES. LLC The site shall be mined and reclaimed concurrently. The miner shall restore the top of the mining phase to reclamation condition as soon as mining is completed in a phase. The operator may not mine Pond 2 below groundwater until Pond 1 is reclaimed to above the groundwater level. The applicant must begin constructing the slope liner after two phases have been completely mined to bedrock by the miner. These conditions will require that reclamation closely follow the active mining process. The effective radius of dewatering as shown in Figure 11a of the Groundwater Model Report is approximately 1500 feet. See Attachment 3 -Water Resources Map for the wells within this radius. No deep wells will be affected because of the hydrologic disconnect between the shallow alluvial aquifer and the deep nontributarv aquifer. 24. No Comment Generated 25. The applicant proposes a variety of mitigation measures on page 9 of the report. The applicant will need to quanti/y the specific mitigation measures to be employed, and specify the location/s) of where such measures will be employed, the length of time for the mitigation measures to be employed, volumes and quality of water to be involved in the mitigation, and how the appropriate volumes and quality of water will be delivered to the various mitigation locations. The applicant will need to specify any structures that will need to be constructed either on-site or offsite in order to deliver the mitigation water. The applicant will need to specify the monitoring measures that will be employed to provide assurance of delivery of the appropriate volume of water and quality of water to be used for mitigation. !n addition to total suspended solids and pli, wafer quality testing will need to include parameters such as total dissolved solids, electrical conductivity, opacity, and palatability (for domestic wells). The applicant will also need to submit a specific map or exhibit which shows the location(s) and type(s) of mitigation measures to be employed. The applicant may also want to consider the use of French Drains between the various cells The mitigation measures to be implemented are discussed in Section 4.2.1 of the Groundwater Model Report and each measure will be implemented in phases as mining proceeds. The length of time that groundwater mitigation will be required depends on how long the mining operation is dewatering in the vicinity. The volume proposed to be delivered, but not limited to, is 500 gallons per minute. The water will be tested for turbidity, conductivity and pH. The water will be delivered by pipe to a recharge site that will contain a vertically oriented perforated pipe that will be installed approximately 15 to 20 feet below the existing ground surface with approximately 15 to 20 feet of 3 foot thick gravel pack surrounding the pipe. The recharge site(s) will meet all regulatory conditions and requirements. Refer to the attached figure illustrating a typical recharge pipe section. See Figure 11a of the Groundwater Model Report for the proposed recharge site locations. Each site will be in proximity of an existing piezometer that will be measured monthly, allowing the applicant to monitor the effects of the proposed mitigation measures. 26. Please clarify whether the post-construction (reclamation/simulation for predicted groundwater impacts considers the impacts to the groundwater system at a time when the compacted clay liner is completed for all cells. If not, the applicant will need fo assess the potential groundwater impacts, such as mounding and/or shadowing, during such time. The assessment of impacts will need to describe the lateral and vertical extent of changes to the existing groundwater system and whether such impacts will intersect offsite structures such as Weld County Road 6, Weld County Road 27,